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<li class="navelem"><a class="el" href="../../d3/d81/tutorial_contrib_root.html">Tutorials for contrib modules</a></li><li class="navelem"><a class="el" href="../../d9/d58/tutorial_table_of_content_quasi_dense_stereo.html">Quasi Dense Stereo (stereo module)</a></li>  </ul>
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<div class="title">Quasi dense Stereo </div>  </div>
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<div class="textblock"><h2>Goal </h2>
<p>In this tutorial you will learn how to</p>
<ul>
<li>Configure a QuasiDenseStero object</li>
<li>Compute dense Stereo correspondences.</li>
</ul>
<div class="fragment"><div class="line"><span class="preprocessor">#include &lt;<a class="code" href="../../d0/d9c/core_2include_2opencv2_2core_8hpp.html">opencv2/core.hpp</a>&gt;</span></div><div class="line"><span class="preprocessor">#include &lt;<a class="code" href="../../d4/dd5/highgui_8hpp.html">opencv2/highgui.hpp</a>&gt;</span></div><div class="line"><span class="preprocessor">#include &lt;fstream&gt;</span></div><div class="line"><span class="preprocessor">#include &lt;<a class="code" href="../../d4/d42/contrib_2modules_2stereo_2include_2opencv2_2stereo_8hpp.html">opencv2/stereo.hpp</a>&gt;</span></div><div class="line"></div><div class="line"></div><div class="line"></div><div class="line"></div><div class="line"><span class="keyword">using namespace </span><a class="code" href="../../d2/d75/namespacecv.html">cv</a>;</div><div class="line"><span class="keyword">using namespace </span>std;</div><div class="line"></div><div class="line"></div><div class="line"><span class="keywordtype">int</span> main()</div><div class="line">{</div><div class="line">    <a class="code" href="../../d3/d63/classcv_1_1Mat.html">cv::Mat</a> rightImg, leftImg;</div><div class="line">    leftImg = <a class="code" href="../../d4/da8/group__imgcodecs.html#ga288b8b3da0892bd651fce07b3bbd3a56">imread</a>(<span class="stringliteral">&quot;./imgLeft.png&quot;</span>, <a class="code" href="../../d8/d6a/group__imgcodecs__flags.html#gga61d9b0126a3e57d9277ac48327799c80af660544735200cbe942eea09232eb822">IMREAD_COLOR</a>);</div><div class="line">    rightImg = <a class="code" href="../../d4/da8/group__imgcodecs.html#ga288b8b3da0892bd651fce07b3bbd3a56">imread</a>(<span class="stringliteral">&quot;./imgRight.png&quot;</span>, <a class="code" href="../../d8/d6a/group__imgcodecs__flags.html#gga61d9b0126a3e57d9277ac48327799c80af660544735200cbe942eea09232eb822">IMREAD_COLOR</a>);</div><div class="line"></div><div class="line"></div><div class="line">    <a class="code" href="../../d6/d50/classcv_1_1Size__.html">cv::Size</a> frameSize = leftImg.<a class="code" href="../../d3/d63/classcv_1_1Mat.html#a146f8e8dda07d1365a575ab83d9828d1">size</a>();</div><div class="line">    <a class="code" href="../../dc/d84/group__core__basic.html#ga6395ca871a678020c4a31fadf7e8cc63">Ptr&lt;stereo::QuasiDenseStereo&gt;</a> stereo = <a class="code" href="../../dd/d86/group__stereo.html#ga67a1543e567dbfaa0b05630951caac2b">stereo::QuasiDenseStereo::create</a>(frameSize);</div><div class="line"></div><div class="line"></div><div class="line">    stereo-&gt;process(leftImg, rightImg);</div><div class="line"></div><div class="line"></div><div class="line">    <a class="code" href="../../d3/d63/classcv_1_1Mat.html">cv::Mat</a> disp;</div><div class="line">    disp = stereo-&gt;getDisparity();</div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga5afdf8410934fd099df85c75b2e0888b">cv::namedWindow</a>(<span class="stringliteral">&quot;disparity map&quot;</span>);</div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga453d42fe4cb60e5723281a89973ee563">cv::imshow</a>(<span class="stringliteral">&quot;disparity map&quot;</span>, disp);</div><div class="line"></div><div class="line"></div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga5afdf8410934fd099df85c75b2e0888b">cv::namedWindow</a>(<span class="stringliteral">&quot;right channel&quot;</span>);</div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga5afdf8410934fd099df85c75b2e0888b">cv::namedWindow</a>(<span class="stringliteral">&quot;left channel&quot;</span>);</div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga453d42fe4cb60e5723281a89973ee563">cv::imshow</a>(<span class="stringliteral">&quot;left channel&quot;</span>, leftImg);</div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga453d42fe4cb60e5723281a89973ee563">cv::imshow</a>(<span class="stringliteral">&quot;right channel&quot;</span>, rightImg);</div><div class="line"></div><div class="line"></div><div class="line">    vector&lt;stereo::MatchQuasiDense&gt; matches;</div><div class="line">    stereo-&gt;getDenseMatches(matches);</div><div class="line">    std::ofstream dense(<span class="stringliteral">&quot;./dense.txt&quot;</span>, std::ios::out);</div><div class="line">    <span class="keywordflow">for</span> (<a class="code" href="../../d1/d1b/group__core__hal__interface.html#ga4f5fce8c1ef282264f9214809524d836">uint</a> i=0; i&lt; matches.size(); i++)</div><div class="line">    {</div><div class="line">        dense &lt;&lt; matches[i].p0 &lt;&lt; matches[i].p1 &lt;&lt; endl;</div><div class="line">    }</div><div class="line">    dense.close();</div><div class="line"></div><div class="line"></div><div class="line"></div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga5628525ad33f52eab17feebcfba38bd7">cv::waitKey</a>(0);</div><div class="line"></div><div class="line">    <span class="keywordflow">return</span> 0;</div><div class="line">}</div></div><!-- fragment --><h2>Explanation:</h2>
<p>The program loads a stereo image pair.</p>
<p>After importing the images. </p><div class="fragment"><div class="line">    <a class="code" href="../../d3/d63/classcv_1_1Mat.html">cv::Mat</a> rightImg, leftImg;</div><div class="line">    leftImg = <a class="code" href="../../d4/da8/group__imgcodecs.html#ga288b8b3da0892bd651fce07b3bbd3a56">imread</a>(<span class="stringliteral">&quot;./imgLeft.png&quot;</span>, <a class="code" href="../../d8/d6a/group__imgcodecs__flags.html#gga61d9b0126a3e57d9277ac48327799c80af660544735200cbe942eea09232eb822">IMREAD_COLOR</a>);</div><div class="line">    rightImg = <a class="code" href="../../d4/da8/group__imgcodecs.html#ga288b8b3da0892bd651fce07b3bbd3a56">imread</a>(<span class="stringliteral">&quot;./imgRight.png&quot;</span>, <a class="code" href="../../d8/d6a/group__imgcodecs__flags.html#gga61d9b0126a3e57d9277ac48327799c80af660544735200cbe942eea09232eb822">IMREAD_COLOR</a>);</div></div><!-- fragment --><p>We need to know the frame size of a single image, in order to create an instance of a <code>QuasiDesnseStereo</code> object.</p>
<div class="fragment"><div class="line">    <a class="code" href="../../d6/d50/classcv_1_1Size__.html">cv::Size</a> frameSize = leftImg.<a class="code" href="../../d3/d63/classcv_1_1Mat.html#a146f8e8dda07d1365a575ab83d9828d1">size</a>();</div><div class="line">    Ptr&lt;stereo::QuasiDenseStereo&gt; stereo = stereo::QuasiDenseStereo::create(frameSize);</div></div><!-- fragment --><p> Because we didn't specify the second argument in the constructor, the <code>QuasiDesnseStereo</code> object will load default parameters.</p>
<p>We can then pass the imported stereo images in the process method like this </p><div class="fragment"><div class="line">    stereo-&gt;process(leftImg, rightImg);</div></div><!-- fragment --><p> The process method contains most of the functionality of the class and does two main things.</p><ul>
<li>Computes a sparse stereo based in "Good Features to Track" and "pyramidal Lucas-Kanade" flow algorithm</li>
<li>Based on those sparse stereo points, densifies the stereo correspondences using Quasi Dense Stereo method.</li>
</ul>
<p>After the execution of <code>process()</code> we can display the disparity Image of the stereo. </p><div class="fragment"><div class="line">    <a class="code" href="../../d3/d63/classcv_1_1Mat.html">cv::Mat</a> disp;</div><div class="line">    disp = stereo-&gt;getDisparity();</div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga5afdf8410934fd099df85c75b2e0888b">cv::namedWindow</a>(<span class="stringliteral">&quot;disparity map&quot;</span>);</div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga453d42fe4cb60e5723281a89973ee563">cv::imshow</a>(<span class="stringliteral">&quot;disparity map&quot;</span>, disp);</div></div><!-- fragment --><p>At this point we can also extract all the corresponding points using <code>getDenseMatches()</code> method and export them in a file. </p><div class="fragment"><div class="line">    vector&lt;stereo::MatchQuasiDense&gt; matches;</div><div class="line">    stereo-&gt;getDenseMatches(matches);</div><div class="line">    std::ofstream dense(<span class="stringliteral">&quot;./dense.txt&quot;</span>, std::ios::out);</div><div class="line">    <span class="keywordflow">for</span> (<a class="code" href="../../d1/d1b/group__core__hal__interface.html#ga4f5fce8c1ef282264f9214809524d836">uint</a> i=0; i&lt; matches.size(); i++)</div><div class="line">    {</div><div class="line">        dense &lt;&lt; matches[i].p0 &lt;&lt; matches[i].p1 &lt;&lt; endl;</div><div class="line">    }</div><div class="line">    dense.close();</div></div><!-- fragment --></div></div><!-- contents -->
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